ABSTRACT
A Faraday-effect radial interferometer-polarimeter is designed for the National Spherical Torus Experiment-Upgrade (NSTX-U) to measure multiscale magnetic and density fluctuations critical to understanding fusion plasma confinement and stability, including those originating from magnetohydrodynamic instabilities, energetic particle-driven modes, and turbulence. The diagnostic will utilize the three-wave technique with 5 MHz bandwidth to simultaneously measure line-integrated magnetic and density fluctuations up to the ion-cyclotron frequency. Probe beams will be launched radially from the low-field side at the NSTX-U midplane, where the measured Faraday fluctuations mainly correspond to radial magnetic fluctuations that directly link to magnetic transport. A correlation technique will be employed to reduce the measurement noise to below 0.01° enabling detection of small amplitude fluctuations. Two toroidally displaced chords with 7° separation will be installed to measure toroidal mode numbers up to n = 25 for mode identification. Solid-state microwave sources operating at 321 µm (935 GHz) will be used to minimize the impact of the Cotton-Mouton effect.
ABSTRACT
A set of new millimeter-wave diagnostics will deliver unique measurement capabilities for National Spherical Torus Experiment-Upgrade to address a variety of plasma instabilities believed to be important in determining thermal and particle transport, such as micro-tearing, global Alfvén eigenmodes, kinetic ballooning, trapped electron, and electron temperature gradient modes. These diagnostics include a new integrated intermediate-k Doppler backscattering (DBS) and cross-polarization scattering (CPS) system (four channels, 82.5-87 GHz) to measure density and magnetic fluctuations, respectively. The system can access reasonably large normalized wavenumbers kθρs ranging from ≤0.5 to 15 (where ion sound gyroradius ρs = 1 cm and kθ is the binormal density turbulence wavenumber). The system addresses the challenges for making useful DBS/CPS measurements with a remote control of launch polarization (X- or O-mode), probed wavenumber, polarization match of the launch beam with the edge magnetic field pitch angle, and beam steering of the launched beam for wave-vector alignment. In addition, a low-k DBS system consisting of eight fixed frequencies (34-52 GHz) and four tunable frequencies (55-75 GHz) for low-k density turbulence and fast ion physics will be located at a nearby port location. The combined systems cover the near LCFS and pedestal regions (34-52 GHz), the pedestal or mid-radius (50-75 GHz), and core plasmas (82.5-87 GHz).
ABSTRACT
A powerful and flexible hard x-ray (HXR) camera has been recently installed and tested on the WEST tokamak (CEA, France) in collaboration with the Princeton Plasma Physics Laboratory. The diagnostic is a pinhole camera fielded with a 2D pixel detector equipped with a 1 mm thick CdTe sensor. The novelty of this diagnostic technique is the detector's capability of adjusting the threshold energy at the pixel level. This innovation provides great flexibility in the energy configuration, allowing simultaneous space, energy, and time resolved x-ray measurements. The novel camera has been used to measure the core radiation from non-Maxwellian (fast) electrons accelerated by Lower Hybrid (LH) waves and also the beam-target emission of tungsten in the divertor region produced by fast electron losses interacting with the target. In addition, anisotropic hard x-ray emission has been detected for the first time at the WEST core and edge plasma, with opposite toroidal intensity trends. Experimental vertical and toroidal HXR profiles have been successfully reproduced with the LH code LUKE.
ABSTRACT
A 693 GHz, eight-channel, poloidal high-k (k refers to wavenumber) collective scattering system is under development for the National Spherical Torus Experiment-Upgrade device. It will replace the previous 280 GHz, five-channel, tangential scattering system to study high-k electron density fluctuations, thereby providing a measurement of the kθ-spectrum of both electron temperature gradient and ion temperature gradient modes. A tool is under development to calculate the wavenumber that exists in the presence of strong magnetic pitch angles. We use this tool to motivate a new receiver optical design for significantly improved performance, details of which are presented herein.
ABSTRACT
WEST (tungsten environment in steady-state tokamak) is starting operation for the first time with a water-cooled full tungsten divertor, enabling long pulse operation. Heating is provided by radiofrequency systems, including lower hybrid current drive (LHCD). In this context, a compact multi-energy hard x-ray camera has been installed for energy and space-resolved measurements of the electron temperature, the fast electron tail density produced by LHCD and runaway electrons, and the beam-target emission of tungsten at the target due to fast electron losses interacting with the divertor plates. The diagnostic is a pinhole camera based on a 2D pixel array detector (Pilatus 3 CdTe CMOS Hybrid-Pixel detector produced by DECTRIS). The novelty of this diagnostic technique is the detector's capability of adjusting the threshold energy at pixel level. This innovation provides great flexibility in the energy configuration, allowing simultaneous space and energy-resolved x-ray measurements. This contribution details two important steps in the preparation of the diagnostic operation. First, the in-vessel spatial calibration that was carried out with a radioactive source. Second, the synthetic diagnostic is obtained by the suite of codes ALOHA/C3PO/LUKE/R5-X2, which simulates LH wave propagation and absorption, as well as the fast electron bremsstrahlung production.
ABSTRACT
A multi-energy soft x-ray pinhole camera has been designed, built, and deployed at the Madison Symmetric Torus to aid the study of particle and thermal transport, as well as MHD stability physics. This novel imaging diagnostic technique employs a pixelated x-ray detector in which the lower energy threshold for photon detection can be adjusted independently on each pixel. The detector of choice is a PILATUS3 100 K with a 450 µm thick silicon sensor and nearly 100 000 pixels sensitive to photon energies between 1.6 and 30 keV. An ensemble of cubic spline smoothing functions has been applied to the line-integrated data for each time-frame and energy-range, obtaining a reduced standard-deviation when compared to that dominated by photon-noise. The multi-energy local emissivity profiles are obtained from a 1D matrix-based Abel-inversion procedure. Central values of Te can be obtained by modeling the slope of the continuum radiation from ratios of the inverted radial emissivity profiles over multiple energy ranges with no a priori assumptions of plasma profiles, magnetic field reconstruction constraints, high-density limitations, or need of shot-to-shot reproducibility. In tokamak plasmas, a novel application has recently been tested for early detection, 1D imaging, and study of the birth, exponential growth, and saturation of runaway electrons at energies comparable to 100 × Te,0; thus, early results are also presented.
ABSTRACT
This paper describes a new class of focusing crystal forms for the x-ray Bragg crystal spectroscopy of small, point-like, x-ray sources. These new crystal forms are designed with the aid of sinusoidal spirals, a family of curves, whose shapes are defined by only one parameter, which can assume any real value. The potential of the sinusoidal spirals for the design x-ray crystal spectrometers is demonstrated with the design of a toroidally bent crystal of varying major and minor radii for measurements of the extended x-ray absorption fine structure near the Ta-L3 absorption edge at the National Ignition Facility.
ABSTRACT
A compact multi-energy soft x-ray diagnostic is being installed on the W Environment in Steady-state Tokamak (WEST), which was designed and built to test ITER-like tungsten plasma facing components in a long pulse (â¼1000 s) scenario. The diagnostic consists of a pinhole camera fielded with the PILATUS3 photon-counting Si-based detector (â²100 kpixel). The detector has sensitivity in the range 1.6-30 keV and enables energy discrimination, providing a higher energy resolution than conventional systems with metal foils and diodes with adequate space and time resolution (â²1 cm and 2 ms). The lower-absorption cut-off energy is set independently on each one of the â¼100 kpixels, providing a unique opportunity to measure simultaneously the plasma emissivity in multiple energy ranges and deduce a variety of plasma parameters (e.g., Te, nZ, and ΔZeff). The energy dependence of each pixel is calibrated here over the range 3-22 keV. The detector is exposed to a variety of monochromatic sources-fluorescence emission from metallic targets-and for each pixel, the lower energy threshold is scanned to calibrate the energy dependence. The data are fit to a responsivity curve ("S-curve") that determines the mapping between the possible detector settings and the energy response for each pixel. Here, the calibration is performed for three energy ranges: low (2.3-6 keV), medium (4.5-13.5 keV), and high (5.4-21 keV). We determine the achievable energy resolutions for the low, medium, and high energy ranges as 330 eV, 640 eV, and 950 eV, respectively. The main limitation for the energy resolution is found to be the finite width of the S-curve.
ABSTRACT
A multi-energy hard x-ray pin-hole camera based on the PILATUS3 X 100K-M CdTe detector has been developed at the Princeton Plasma Physics Laboratory for installation on the Tungsten Environment in Steady State Tokamak. This camera will be employed to study thermal plasma features such as electron temperature as well as non-thermal effects such as fast electron tails produced by a lower hybrid radiofrequency current drive and the birth of runaway electrons. The innovative aspect of the system lies in the possibility of setting the threshold energy independently for each of the â¼100k pixels of the detector. This feature allows for the measurement of the x-ray emission in multiple energy ranges with adequate space and time resolution (â¼1 cm, 2 ms) and coarse energy resolution. In this work, the energy dependence of each pixel was calibrated within the range 15 keV-100 keV using a tungsten x-ray tube and emission from a variety of fluorescence targets (from yttrium to uranium). The data corresponding to pairs of Kα emission lines are fit to the characteristic responsivity ("S-curve"), which describes the detector sensitivity across the 64 possible energy threshold values for each pixel; this novel capability is explored by fine-tuning the voltage of a six-bit digital-analog converter after the charge-sensitive amplifier for each of the â¼100k pixels. This work presents the results of the calibration including a statistical analysis. It was found that the achievable energy resolution is mainly limited by the width of the S-curve to 3 keV-10 keV for threshold energies up to 50 keV, and to ≥20 keV for energies above 60 keV.
ABSTRACT
An 8-channel, high-k poloidal far-infrared (FIR) scattering system is under development for the National Spherical Torus eXperiment Upgrade (NSTX-U). The 693 GHz poloidal scattering system replaces a 5-channel, 280 GHz high-k toroidal scattering system to study high-k electron density fluctuations on NSTX-U. The FIR probe beam launched from Bay G is aimed toward Bay L, where large aperture optics collect radiation at 8 simultaneous scattering angles ranging from 2° to 15°. The reduced wavelength in the poloidal system results in less refraction, and coupled with a new poloidal scattering geometry, extends measurement of poloidal wavenumbers from the previous limit of 7 cm-1 up to >40 cm-1. Steerable launch optics coupled with receiver optics that can be remotely translated in 5 axes allow the scattering volume to be placed from r/a = 0.1 out to the pedestal region (r/a â¼ 0.99) and allow for both upward and downward scattering to cover different regions of the 2D fluctuation spectrum.
ABSTRACT
The here-described spectrometer was developed for the extended x-ray absorption fine structure spectroscopy of high-density plasmas at the National Ignition Facility. It employs as the Bragg reflecting element a new type of toroidally bent crystal with a constant and very large major radius R and a much smaller, locally varying, minor radius r. The focusing properties of this crystal and the experimental arrangement of the source and detector make it possible to (a) fulfill the conditions for a perfect imaging of an ideal point source for each wavelength, (b) obtain a high photon throughput, (c) obtain a high spectral resolution by eliminating the effects of source-size broadening, and (d) obtain a one-dimensional spatial resolution with a high magnification perpendicular to the main dispersion plane.
ABSTRACT
A new tool has been developed to calculate the spectral, spatial, and temporal responses of multi-energy soft x-ray (ME-SXR) pinhole cameras for arbitrary plasma densities (n e,D), temperature (T e), and impurity densities (n Z). ME-SXR imaging provides a unique opportunity for obtaining important plasma properties (e.g., T e, n Z, and Z eff) by measuring both continuum and line emission in multiple energy ranges. This technique employs a pixelated x-ray detector in which the lower energy threshold for photon detection can be adjusted independently. Simulations assuming a tangential geometry and DIII-D-like plasmas (e.g., n e,0 ≈ 8 × 1019 m-3 and T e,0 ≈ 2.8 keV) for various impurity (e.g., C, O, Ar, Ni, and Mo) density profiles have been performed. The computed brightnesses range from few 102 counts pixel-1 ms-1 depending on the cut-off energy thresholds, while the maximum allowable count rate is 104 counts pixel-1 ms-1. The typical spatial resolution in the mid-plane is ≈0.5 cm with a photon-energy resolution of 500 eV at a 500 Hz frame rate.
ABSTRACT
A multi-energy soft x-ray pinhole camera has been designed and built for the Madison Symmetric Torus reversed field pinch to aid the study of particle and thermal-transport, as well as MHD stability physics. This novel imaging diagnostic technique combines the best features from both pulse-height-analysis and multi-foil methods employing a PILATUS3 x-ray detector in which the lower energy threshold for photon detection can be adjusted independently on each pixel. Further improvements implemented on the new cooled systems allow a maximum count rate of 10 MHz per pixel and sensitivity to the strong Al and Ar emission between 1.5 and 4 keV. The local x-ray emissivity will be measured in multiple energy ranges simultaneously, from which it is possible to infer 1D and 2D simultaneous profile measurements of core electron temperature and impurity density profiles with no a priori assumptions of plasma profiles, magnetic field reconstruction constraints, high-density limitations, or need of shot-to-shot reproducibility. The expected time and space resolutions will be 2 ms and <1 cm, respectively.
ABSTRACT
A prototype of an infrared imaging bolometer (IRVB) was successfully tested on the Alcator C-Mod tokamak at the end of its 2016 campaign. The IRVB method interprets the power radiated from the plasma by measuring the temperature rise of a thin, â¼2 µm, Pt absorber that is placed in the torus vacuum and exposed, using a pinhole camera, to the full-spectrum of plasma's photon emission. The IRVB installed on C-Mod viewed the poloidal cross section of the core plasma and observed Ohmic and ion cyclotron range of frequency (ICRF)-heated plasmas. Analysis of total radiated power and on-axis emissivity from IRVB is summarized, and quantitative comparisons made to data from both resistive bolometers and AXUV diodes. IRVB results are clearly within a factor of two, but additional effort is needed for it to be used to fully support power exhaust research. The IRVB is shown to be immune to electromagnetic interference from ICRF which strongly impacts C-Mod's resistive bolometers. Results of the bench-top calibration are summarized, including a novel temperature calibration method useful for IRVBs.
ABSTRACT
Kaposi sarcoma (KS) is a malignancy of viral etiology whose course ranges from cutaneous limited lesions to fulminant disease with multi-organ involvement. Four clinical variants of the disease exist: classic, endemic, iatrogenic, and epidemic. Iatrogenic and epidemic variants of Kaposi sarcoma develop in the setting of immune suppression. Transplant recipients who develop iatrogenic KS typically demonstrate improvement of lesions following de-escalation of immunosuppressive therapy. Similarly, HIV-infected patients who begin highly active antiretroviral therapy (HAART) experience immune reconstitution, which can induce KS regression. We describe two patients with varying clinical outcomes of cutaneous-limited HIV-associated KS after immune reconstitution with HAART. We propose that immune reconstitution with HAART, followed by clinical and radiographic surveillance for disease progression, may be an appropriate initial management strategy for limited cutaneous HIV-associated KS. In patients with more extensive disease at presentation or failure of HAART alone, antineoplastic therapy should be instituted.
Subject(s)
AIDS-Related Opportunistic Infections/drug therapy , Antiretroviral Therapy, Highly Active , Sarcoma, Kaposi/drug therapy , Skin Neoplasms/drug therapy , AIDS-Related Opportunistic Infections/pathology , Adult , HIV Infections/complications , HIV Infections/drug therapy , Humans , Male , Middle Aged , Sarcoma, Kaposi/pathology , Skin Neoplasms/pathologyABSTRACT
BACKGROUND: Sexually transmitted infections, includingurogenital gonorrheal infection, are a growing healthconcern in the United States. Nearly 50% of cervicalinfections are asymptomatic. If left undiagnosedand untreated, there is a risk of disseminatedinfection. PURPOSE: To describe an 18-year-old womanpresenting with disseminated gonococcal infectionconfirmed by blood cultures, skin biopsy, and urinegonococcal probe. We also describe the presentation,diagnosis, and treatment of disseminated gonococcalinfection, including discussion of the variousmorphologies of cutaneous lesions that have beenreported in the literature. MATERIALS AND METHODS: Thefeatures of a woman with disseminated gonococcalinfection are presented. Using PubMed, the termscutaneous, disseminated, gonococcal, gonorrhea,infection, lesions, manifestations, pustules, skin, andsystemic were searched. Relevant citations wereutilized and discussed. RESULTS: Hemorrhagic pustules,petechiae, and purpuric lesions developed in a youngwoman with fever and joint pain. Blood cultures grewbeta lactamase negative Neisseria gonorrhoeae andthe Neisseria gonorrhoeae/Chlamydia trachomatisprobe was positive for both N. gonorrhoeae and C.trachomatis. Biopsy revealed bulla with neutrophils,extravasated erythrocytes, fibrin deposits in the vesselwalls, and leukocytoclasia. CONCLUSION: Cutaneouslesions of disseminated gonococcal infection caninclude abscesses, cellulitis, petechiae, purpuricmacules, necrotizing fasciitis, and vasculitis. It isimportant for the clinician to recognize the clinicalsigns and symptoms of disseminated gonococcalinfection, particularly the various cutaneousmanifestations.
Subject(s)
Arthritis, Infectious/diagnosis , Bacteremia/diagnosis , Dermatitis/diagnosis , Gonorrhea/diagnosis , Adolescent , Anti-Bacterial Agents/therapeutic use , Arthritis, Infectious/drug therapy , Bacteremia/drug therapy , Ceftriaxone/therapeutic use , Dermatitis/drug therapy , Dermatitis/pathology , Female , Gonorrhea/drug therapy , Humans , Neisseria gonorrhoeaeABSTRACT
BACKGROUND: Radiation recall dermatitis (RRD) canpresent days to years after radiation exposure andis most commonly caused by chemotherapy drugs,with tamoxifen-induced radiation recall dermatitisbeing exceptionally rare. PURPOSE: To report a newcase of tamoxifen-induced radiation recall dermatitisafter 4.5 years of tamoxifen exposure, making this thelongest time of onset to RRD after tamoxifen initiation. MATERIALS AND METHODS: The case of a woman withtamoxifen-induced RRD is presented. Using PubMedand Google Scholar, the terms tamoxifen, radiation,recall, dermatitis were searched. Relevant citationswere utilized and discussed. RESULTS: An adult womanwith history of inflammatory breast carcinomadeveloped an erythematous, scaly, tender plaquelocalized to previously irradiated skin of the left chestafter more than four years of tamoxifen therapy. Thepatient was diagnosed with RRD and was treated withtopical triamcinolone 0.1% cream twice daily to theaffected areas. The patient experienced subsequentrapid improvement despite continuation of tamoxifentreatment. Biopsy revealed changes consistent withradiation dermatitis with no evidence of malignancy. CONCLUSION: Radiation recall dermatitis can havesignificant impact on affected patients and can posea diagnostic dilemma for clinicians who may mistakeRRD for infection or recurrence of malignancy. It isimportant to be familiar with the presenting signs andsymptoms of this entity so that affected patients canreceive timely and appropriate therapy.
Subject(s)
Antineoplastic Agents, Hormonal/adverse effects , Carcinoma/therapy , Inflammatory Breast Neoplasms/therapy , Radiodermatitis/chemically induced , Tamoxifen/adverse effects , Administration, Cutaneous , Female , Glucocorticoids/therapeutic use , Humans , Mastectomy , Middle Aged , Radiodermatitis/diagnosis , Radiodermatitis/drug therapy , Radiodermatitis/pathology , Radiotherapy , Triamcinolone/therapeutic useABSTRACT
Dermatofibromas are benign, fibrohistiocytic, dermal tumors. Solitary dermatofibromas may be incidental findings, whereas multiple dermatofibromas may be associated with systemic conditions or previous therapies. Two women and one man with multiple dermatofibromas and an associated systemic condition, immunosuppression, or both, are described. Nine dermatofibromas developed in a woman with hypothyroidism, optic neuritis, and Arnold Chiari I malformation. Five dermatofibromas developed in a woman with breast cancer who had received several systemic antineoplastic therapies. Eleven dermatofibromas developed in a man with HIV whose systemic therapies included acyclovir, darunavir/cobicistat, dolutegravir, etravirine, and ritonavir. Conditions associated with multiple dermatofibromas include autoimmune diseases, cancer, chromosomal abnormalities, immunodeficiencies, metabolic disturbances, and altered physiologic states such as pregnancy. Medications received by patients with multiple dermatofibromas included immunosuppressive agents, psoriasis therapies, and antineoplastic drugs. Multiple dermatofibromas can be observed in patients with associated medical conditions, systemic therapies, or both. Therefore, in individuals presenting with multiple dermatofibromas, not only evaluation for associated disorders, but also review of prior and current drug therapies, should be considered.
Subject(s)
Breast Neoplasms/complications , HIV Infections/complications , Histiocytoma, Benign Fibrous/etiology , Hypothyroidism/complications , Adolescent , Adult , Antineoplastic Agents/adverse effects , Arnold-Chiari Malformation/complications , Breast Neoplasms/drug therapy , Female , HIV Infections/drug therapy , Histiocytoma, Benign Fibrous/pathology , Humans , Immunocompromised Host , Immunosuppressive Agents/adverse effects , Male , Middle Aged , Optic Neuritis/complicationsABSTRACT
A radiative divertor technique is planned for the NSTX-U tokamak to prevent excessive erosion and thermal damage of divertor plasma-facing components in H-mode plasma discharges with auxiliary heating up to 12 MW. In the radiative (partially detached) divertor, extrinsically seeded deuterium or impurity gases are used to increase plasma volumetric power and momentum losses. A real-time feedback control of the gas seeding rate is planned for discharges of up to 5 s duration. The outer divertor leg plasma electron temperature Te estimated spectroscopically in real time will be used as a control parameter. A vacuum ultraviolet spectrometer McPherson Model 251 with a fast charged-coupled device detector is developed for temperature monitoring between 5 and 30 eV, based on the Δn = 0, 1 line intensity ratios of carbon, nitrogen, or neon ion lines in the spectral range 300-1600 Å. A collisional-radiative model-based line intensity ratio will be used for relative calibration. A real-time Te-dependent signal within a characteristic divertor detachment equilibration time of â¼10-15 ms is expected.
ABSTRACT
Soft x-ray detection with the new "multi-energy" PILATUS3 detector systems holds promise as a magnetically confined fusion (MCF) plasma diagnostic for ITER and beyond. The measured x-ray brightness can be used to determine impurity concentrations, electron temperatures, ne2Zeff products, and to probe the electron energy distribution. However, in order to be effective, these detectors which are really large arrays of detectors with photon energy gating capabilities must be precisely calibrated for each pixel. The energy-dependence of the detector response of the multi-energy PILATUS3 system with 100 K pixels has been measured at Dectris Laboratory. X-rays emitted from a tube under high voltage bombard various elements such that they emit x-ray lines from Zr-Lα to Ag-Kα between 1.8 and 22.16 keV. Each pixel on the PILATUS3 can be set to a minimum energy threshold in the range from 1.6 to 25 keV. This feature allows a single detector to be sensitive to a variety of x-ray energies, so that it is possible to sample the energy distribution of the x-ray continuum and line-emission. PILATUS3 can be configured for 1D or 2D imaging of MCF plasmas with typical spatial energy and temporal resolution of 1 cm, 0.6 keV, and 5 ms, respectively.